Mod makers can add extra joints
I know this probably isn't a good idea, however it opens up new possibilities to mods. I have a good idea for an interface for this. In the mod maker, there will be a menu where you can select whole body parts (legs, arms, torso, etc) or just individual joints (ankles, lumbar, etc). Then you just drag it to wherever you like on the tori or uke's body, then whoevers body it's put on, it'll be controllable by that person. Again, may not be a good concept, but it allows for more fun mods to be made to be compatible with 2 players, like a 4 armed duel, because it doesn't require any removing from either player.